In celebration of the 40-year legacy of Movement Disorders Journal (MDJ), this historical reflection traces the evolution of epidemiological research in movement disorders through the lens of papers published in MDJ from 1986 through 2025. Over four decades, the discipline has transformed from clinic-based descriptive observations into population-based methodologies, with both genetic and environmental factors taken into consideration. The initial decade (1986-1995) established foundational measures of movement disorders and identified key environmental risks. These clinic-based studies expanded during the second decade (1996-2005) into door-to-door community prevalence studies and health services research utilizing administrative databases. The third decade (2006-2015) marked a paradigm shift driven by genetic epidemiology (particularly the mapping of global LRRK2 variants), gene-environment interactions, and the characterization of prodromal biomarkers. The modern era (2016-2025) has embraced race-ethnicity diversity, pharmacoepidemiology, and advanced causal inference methods to control for time-varying factors. Together, these epidemiological works in MDJ chart a historical trajectory toward precision medicine, delivering the infrastructure to define at-risk populations and deploy trial-ready cohorts for disease-modification trials. © 2026 International Parkinson and Movement Disorder Society.

Apathy is one of the most prevalent and disabling non-motor symptoms in Parkinson's disease (PD) and dementia with Lewy bodies (DLB), collectively referred to as Lewy body disorders (LBDs). It is associated with reduced quality of life, accelerated cognitive decline, increased caregiver burden, and poorer functional outcomes, yet remains underrecognized and undertreated. A Working Group of the International Parkinson and Movement Disorder Society's Non-Motor Symptoms Study Group conducted a comprehensive review of the literature and developed a position paper through iterative expert discussion and critical appraisal of available data. This review aims to provide a structured, expert-informed synthesis of the current evidence on the clinical features, neurobiology, assessment, and management of apathy in LBDs and to define priorities for future research and clinical trials. Apathy in LBDs is a multidimensional syndrome encompassing reward insensitivity, negative affect, executive dysfunction, and auto-activation deficits. Converging evidence implicates dysfunction within distributed frontal-striatal-limbic networks and multi-neurotransmitter systems, including dopaminergic, serotonergic, noradrenergic, and cholinergic pathways. Although several pharmacological and nonpharmacological interventions have been explored, few randomized controlled trials have specifically targeted apathy, and no treatment can currently be considered definitively efficacious. Methodological heterogeneity, inadequate phenotyping, and inconsistent outcome measures have limited therapeutic progress. Apathy should be recognized as a primary clinical and research priority in LBDs. Future adequately powered, mechanistically informed trials using standardized diagnostic criteria and validated outcome measures are urgently needed to advance treatment development. © 2026 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.